The present invention relates to rail car truck shear pads which are conventionally used to support side frame pedestals on roller bearing adapters, with the adapters customarily supporting the rail car truck side frames on the truck wheel sets. Typically, such shear pads are not interlocked with or secured to the side frame pedestal or the roller bearing adapter in a manner which would prevent movement of these elements relative to each other in a direction parallel to the longitudinal dimension of the side frame. By securing the shear pads to both the roller bearing adapter and the side frame pedestal, the speed at which a rail car truck hunts will be substantially increased.
Typical shear pads used in the described environment in the past have tended to slip at the interfaces between the shear pad and the side frame pedestal and between the shear pad and the roller bearing adapter. When such slippage occurs, the effective stiffness of the shear pad is greatly reduced and hunting is initiated. The stiffness of the shear pad greatly affects truck inter-axle shear stiffness. As the inter-axle shear stiffness increases, the threshold of truck hunting rises. Thus, shear pad slipping instantaneously reduces the effective inter-axle shear stiffness of the rail car truck. By interlocking the shear pad to both the side frame pedestal and the roller bearing adapter, it is possible to substantially increase the speed at which truck hunting occurs.
The present invention relates to rail car trucks and in particular to an improved shear pad for supporting the side frame pedestals on the related roller bearing adapters.
A primary purpose of the invention is a shear pad for the described environment which has formed thereon structure which enables the shear pad to be interlocked with both the side frame pedestal and the roller bearing adapter.
Another purpose of the invention is to provide a shear pad for the use described in which there are a plurality of steel plates encapsulated by an elastomeric material and in which the shear pad is interlocked with both the roller bearing adapter and the side frame pedestal, preventing relative movement between these elements in the direction of the longitudinal dimension of the side frame.
Other purposes will appear in the ensuing specification, drawings and claims.